A differentially fed rectangular dielectric resonator antenna (DRA) is presented. The DRA is excited by a microstrip gap between two identical transmission lines carrying a differential signal. It is shown that this new method can be adopted to excite the fundamental TE1δ1 mode in a rectangular DRA. Furthermore, by adding a stub to each transmission line, an additional nonradiating resonance is obtained that results in bandwidth enhancement. A conventional hybrid (rat-race) coupler is used for a single-end operation. A common ground plane is shared between the DRA (placed in + z -plane) and the hybrid coupler (placed in –z -plane) to preserve the footprint of the antenna. For | S 11| ≤ –10 dB, a wide impedance bandwidth of 30% is measured from 2.27 to 3.07 GHz. Additionally, a surface-mounted short horn (SMSH) is incorporated to enhance the boresight gain throughout the band. In measurements, an optimum boresight gain of 12.2 dBi with an improvement of 5.8 dB is obtained at 2.6 GHz using the proposed DRA with SMSH.

Differentially Fed Wideband Rectangular DRA With High Gain Using Short Horn

In this article, a rigorous full-wave analysis for determining the resonant frequency and half-power bandwidth of inverted circular microstrip patch antenna is presented. Green's functions of the structure are determined in Hankel transform domain. Galerkin's is used in the resolution of the electric field integral equation. The TM set modes issued from the cavity model theory are used to expand to unknown current on the patch. The validity of the results is tested by comparing results with the experimental data. Also, numerical results for the variation of the resonant characteristics of the structure for high-order mode, and for several values of substrates thickness are presented. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2422–2425, 2014

Efficient full-wave analysis of inverted circular microstrip antenna

In this paper, a differentially excited quad-element multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) is proposed for millimeter-wave applications. In the proposed design, the rectangular DRA is differentially excited in the $TE_{1\delta 1}^{y}$ mode using the dual-slot configuration located on the top wall of $TE_{20}$ mode substrate integrated waveguide (SIW). The proposed MIMO configuration offers both spatial and polarization diversities. For all the four ports, the impedance bandwidth of the proposed antenna is 3.2% (27.5-28.4 GHz), covering the 5G frequency spectrum. The isolation between the input ports is better than 40 dB throughout the operating bandwidth. The antenna radiates along the broadside direction having the cross-polarization level below -30 along the zenith. The peak gain and radiation efficiency of the proposed antenna is 4.2 dBi and 86%, respectively at 28 GHz. Moreover, the diversity performance is found to be good having low value of envelope correlation coefficient across the band-width. The proposed antenna could be the potential candidate for next generation 5G communication system.

Millimeter-Wave Quad-Port Multiple-Input Multiple-Output Dielectric Resonator Antenna Excited Differentially by TE 20 Mode Substrate Integrated Waveguide

In this article tunable characteristic of differentially fed inverted microstrip patch antenna is presented for C-band operation. Differential feeding is applied through a unilayer integrated coupler feed. Near the operating frequency of the designed antenna the fabricated coupler shows that the amplitude imbalance is 0.3 dB and phase imbalance corresponds to 3.2°. Tuning is achieved by changing the air gap height in the antenna structure from 1 to 4 mm. Proposed concept of tunablity is verified for two different patch geometries (circular and rectangular) and three different patch dimensions through analysis and experiments. Closed form expressions are proposed to predict the tuning frequency. This design offers low cross-polarized radiation in the H-plane and symmetric co-polarized radiation in both principal planes. Fabricated prototype is measured and compared with simulated and theoretical values. The comparison among the simulated values, theoretically computed values and the measured values for different air gap heights of 2, 3, and 4 mm, shows an error less than 1%.

Frequency Tunable Differentially Fed Inverted Microstrip Patch Antenna with Low Cross-Polarized Radiation

In this paper, we propose a full-wave analysis for characterizing the resonant frequencies and bandwidths of high-temperature superconductor inverted microstrip printed on anisotropic substrates. Our proposed approach is based on Galerkin procedure in the Fourier transform domain (FTD) combining with the complex resistive boundary condition. With the use of suitable Green's functions in the FTD, the analysis is performed for the case where the superconducting rectangular patches printed on anisotropic substrate. The numerical results obtained using the proposed approach are compared with previously published numerical results computed by means of the electromagnetic simulator “IE3D software”. These comparisons were very good, which prove the correctness and the validity of the proposed method. It is found that the optical properties combined with optimally chosen structural parameters of anisotropic materials can be maintaining control of the resonant frequency and exhibiting wider bandwidth characteristics.

Inverted HTS rectangular patch antennas: Theoretical investigation

This letter presents a compact design of an inverted microstrip circular patch differentially fed by an integrated coupler. The compact design offers symmetric copolarized radiation in both principal planes and low cross-polarized radiation in the H-plane. A relatively high gain of 8.3 dBi is experimentally demonstrated. Moreover, the integrated unilayer coupler feed shares a common ground plane with the inverted patch providing a compact design.

Compact Differentially Fed Inverted Microstrip Circular Patch With an Integrated Coupler

This paper investigates the differentially fed circular microstrip antenna in inverted configuration. Compared to single fed microstrip antennas, the differentially fed configuration offers wider impedence bandwidth, symmetric copolarized radiation and lower cross-polarized radiation. Moreover, the inverted configuration of the differentially fed design exhibits wider gain than conventional differentially fed design. Simulation results for different configurations are compared and presented in this paper.

A novel differentially fed inverted circular microstrip antenna

The input resistance at resonance of the microstrip patch is an important parameter to be determined for proper impedance matching of the feed with the patch to achieve optimum performance. In this paper we have investigated the change in the input resistance at resonance for different feed position of a probe fed slotted rectangular and square microstrip patches.

Investigation of varying resonant resistance of the slotted rectangular patch

A compact differentially fed inverted microstrip patch antenna with frequency tunable characteristic is presented in this paper. Tuning of resonance frequency is achieved by changing the air gap height. Theoretical estimation of the resonant frequency is presented for two different patch geometries. High co-polarization to cross-polarization discrimination is achieved due to the differential feed. Theoretical results are validated with simulation and measured values.

J.Y. Siddiqui

Papers

Compact Differentially Fed Inverted Microstrip Circular Patch With an Integrated Coupler

Frequency Tunable Differentially Fed Inverted Microstrip Patch Antenna with Low Cross-Polarized Radiation

A novel differentially fed inverted circular microstrip antenna

Investigation of varying resonant resistance of the slotted rectangular patch

Tunable differentially fed inverted microstrip patch antenna